Presentation
Work up for trauma.
Patient Data
Age: 25 years
Gender: Male
From the case:
Lightbulb sign - posterior shoulder dislocation
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The humeral head is forced into the internal rotation as it dislocates posteriorly, giving the appearance of a lightbulb sign.
Case Discussion
Posterior dislocation of the right shoulder on frontal projection can be difficult to identify. Note the poor congruency of the glenohumeral line, not forming a nice lens and the lightbulb shape of the rotated humeral head.